function figure_sparseclustering()
    numpoints = 20;
    x1=randint(1,numpoints,[-200,200]);
    y1=2*x1+randn(1,numpoints); % 2x1+x2-x3=0
    x2=randint(1,numpoints,[-200,200]);
    y2=x2+randn(1,numpoints); % 3x1-5x2-x3=0
    x=[x1,x2];
    y=[y1,y2];
    data=[ x',y'];
    plot(x,y,'r.');
end
